Drivers heading north into San Francisco on the storied 101 Freeway will find a white billboard with a message in plain black text: "Your Data Should Belong To The NSA."

It seems like someone's trying to send a message about Silicon Valley's relationship with the government agency, but it's unclear who. No one knows who paid for it. The Los Angeles Times reports:

"Guessing the identity of the organization or person behind the sign has become one of Silicon Valley's favorite parlor games in recent days.

"Of course, it's possible that despite creepy, Big Brother-ish overtones, that it's the NSA itself just trying to get some good marketing.

"Others have wondered, could it be the work of Michael Arrington, erstwhile blogger-turned-venture-capitalist-turned conscience of Silicon Valley? Arrington has been on a one-man crusade to shame valley companies that have been assisting NSA efforts. As Arrington recently said on his blog: 'I'm scared of our government and I'm disgusted by what little Silicon Valley has done to fight it.'

"Or could it be the mysterious Billboard Liberation Front, the guerrilla urban art pranksters known for altering signs around the Bay Area to feature subversive slogans? These were the folks who climbed up another billboard on Highway 101 in San Francisco back in 2001 to mock the dot-com bust by altering a Fortune Magazine ad featuring Jeff Bezos.

"They changed the text from 'In the land of the blind ...' to 'In the land of the dead ...' and put pennies over Bezos' eyes (a gesture made to those who are dead.)"